Landau-Zener interference at bichromatic driving

Florian Forster, Max Mühlbacher, Ralf Blattmann, Dieter Schuh, Werner Wegscheider, Stefan Ludwig, and Sigmund Kohler
Phys. Rev. B 92, 245422 (2015)We investigate experimentally and theoretically the
interference at avoided crossings which are repeatedly traversed as a
consequence of an applied ac field. Our model system is a charge qubit in a
serial double quantum dot connected to two leads. Our focus lies on effects
caused by simultaneous driving with two different frequencies. We work out how
the commensurability of the driving frequencies affects the symmetry of the
interference patterns both in real space and in Fourier space. For
commensurable frequencies, the symmetry depends sensitively on the relative
phase between the two modes, whereas for incommensurable frequencies the
symmetry of monochromatic driving is always recovered.
arXiv:1510.01976 [cond-mat]